[jQuery] "No such interface supported" error in Internet Explorer

[0xCAFE]

Hi,

I have a CheckUsername function where using Ajax and jQuery, I check
if the supplied username is already in use in the database.  It works
fine with Firefox, but with IE, I always get this JavaScript error :

"No such interface supported"

And it always falls in the error: part of the code.

function checkUsername() {

        // Removed Ajax result
        $("#username_status").html("");

        // If there is already a validation error, don't bother with
username verification
        if( $("#txtUserName").parent(".error").length > 0 )
          return;

        username = $("#txtUserName").val();

        if ((previous_username != username) && (username != '') &&
(in_ajax != 1)) {
            in_ajax = 1;
            $("#username_status").html("<img src='loading.gif'
border='0' valign='middle' alt='Loading...' />");
            try {
              $.ajax({
                type: "GET",
                data: {txtUserName: username},
                url: '/AJAXCheckUsername.jsp' + '&time=' + (new
Date()).getTime(),
                timeout: 5000,
                success: function(data) {
                           in_ajax = 0;
                           if( data == "Available" ) {
                             $("#username_status").html('<img
src="accept.png" border="0" alt="Available" style="vertical-align:
middle;" /> Username is Available!');
                             $
("#txtUserName").parent().removeClass("error");
                           } else if( data == "Not Available" ) {
                             $("#username_status").html('<img
src="cross.png" border="0" alt="Not Available" style="vertical-align:
middle;" /> Sorry.  This username is already taken.');
                             $
("#txtUserName").parent().addClass("error");
                           } else {
                             $("#username_status").html('<img
src="error.gif" border="0" alt="Error" style="vertical-align:
middle;" /> An Error Has Occured!');
                             $
("#txtUserName").parent().addClass("error");
                           }
                         },
                error: function(data) {
                          $("#username_status").html('An Error has
occured. Please retry.');
                       }
              });
            } catch(error) {
              console.log("Error : " + error.toString());
            }
        }

        previous_username = username;
    }

I read something about not being able to write to the document with
data from an external document here
http://groups.google.com/group/jquery-en/browse_thread/thread/e05ac9803242a7b7/e7582413b496d187

Is there a way to make this code work ?

Thanks!